Numerical modeling of the large-scale neutral and plasma responses to the body forces created by the dissipation of gravity waves from 6 h of deep convection in Brazil

We study the response of the thermosphere and ionosphere to gravity waves (GWs) excited by 6 h of deep convection in Brazil on the evening of 01 October 2005 via the use of convective plume, ray trace, and global models. We find that primary GWs excited by convection having horizontal wavelengths of λ_H∼70-300 km, periods of 10-60 min, and phase speeds of c_H∼50-225 m/s propagate well into the thermosphere. Their density perturbations are ρ′/ρ̄∼15- 25% at z∼150 km and are negligible at z>300 km. The dissipation of these GWs creates spatially and temporally localized body forces with amplitudes of 0.2- 1.0 m/s²at z∼120-230 km. These forces generate two counter-rotating circulation cells with horizontal velocities of 50-350 m/s. They also excite secondary GWs; those resolved by our global model have λ_H∼4000-5000 km and c_H∼500-600 m/s. These secondary GWs propagate globally and have ρ′/ρ̄∼10- 25% and 5-15% at z=250 and 375 km, respectively. These forces also create plasma perturbations of f _oF2^′∼0.2-1.0 MHz, TEC^′∼0.4- 1.5 TECU (total electron content unit, 1TECU =10¹⁶ elm ^-2), and h_mF2^′∼5-50 km. The large-scale traveling ionospheric disturbances (LSTIDs) induced by the secondary GWs have amplitudes of f_oF2^′∼0.2-0.5 MHz, TEC^′∼0.2- 0.6 TECU, and h_mF2 ^′∼5-10 km. In a companion paper, we discuss changes to the prereversal enhancement and plasma drift from these forces. Key PointsThe dissipation of GWs creates circulation cells, secondary GWs, LSTIDs